A known exhaust drain valve for a fuel cell is disclosed in JP2013-093256A (hereinafter referred to as Patent reference 1). As disclosed in Patent reference 1, a primary flow passage of the exhaust drain valve for the fuel cell includes an orifice and an introduction flow passage. The orifice is communicated with a primary flow passage outlet. The introduction flow passage is formed in a tapered shape and that connects the orifice to an inlet.
According to the aforementioned exhaust drain valve for the fuel cell disclosed in Patent reference 1, when the exhaust drain valve is opened in a state where a produced water is gathered, the produced water (liquid) is drained, and at the same time, an anode off-gas (a gaseous material) flows simultaneously (gas-liquid two-phase flow). In this time, because a slug flow is generated in the primary flow passage, an abnormal noise is generated.
A need thus exists for an exhaust drain valve for a fuel cell which is not susceptible to the drawback mentioned above.